Ingot mold



June 7,, 1949. J E. GATHMANN GOT HOLD Filed Sept. 4, 1 5

1 k E 4 r i5 Patented June 7, 1949 moor MOLD,

Emil Gathmann, Baltimore, Md., assignor to Gathmann Research Incorporated, Catonsville, Md., a corporation of Maryland Application September 4, 1945, Serial No. 614,377

Claims. (01. 22-139) This invention relates to ingot molds, and more particularly to big-end-down ingot molds, that is ingot molds of the kind in which the matrix cross section gradually diminishes from bottom to top.

Reference is made to my copending application Serial No. 609,066, filed August 6, 1945 of which the present application is a continuation in part.

Big-end-down molds are open at both top and bottom and the standard practice is to support the mold proper, comprising the matrix side walls, on a stool which forms the bottom of the mold matrix. After an ingot has been poured and has solidified, the mold proper is stripped from the ingot which remains on the stool. Such molds may be of various cross sectional contourspsuch as substantially rectangular with rounded corners, polygonal, or corrugated or rippled. I have found that, irrespective of the cross sectional contour of a big-end-down mold, the mold becomes unserviceable by wearing out as by cracking, checking, or spalling off at and immediately adjacent its lower portion before the intermediate and upper portions have been substantially damaged. Thus, damaging of a relatively small part of the mold makes it necessary to scrap the whole mold while the other portions of the mold are still in good condition. Furthermore there is an intermediate period in the life of a mold during which the damage at the bottom may seem to be small enough, particularly because of its being confined to the bottom, to justify continuing the mold in use. However, tests have shown that ingots cast in big-end-down molds damaged only near their bottoms and still not substantially damaged in their upper and intermediate ports have more defects than ingots cast in big-end-down molds with sound bottom portions.

An object of the present invention is to provide a new and improved big-end-down ingot mold which is so constructed as to render the bottom portion less vulnerable to the action of hot ingot metal and to thus eliminate or minimize the tendency for the bottom portion to spall off, check, crack, or erode more quickly than other parts of the mold.

Although big-end-clown molds of different cross .I. sectional contours have been in use for many years, it has been the standard practice for the lower matrix side walls, of whatever shape in horizontal section, to meet or intersect the planar bottom face of the mold proper at an abrupt, sharp. and substantially right-angular edge. I have found that this sharp or angular edge at the small radius. Preferably the radius is of the order I of about two to three percent of the maximum matrix cross sectional dimension on a neutral axis in the most commonly used sizes-of commercial molds. By neutral axis is meant a line passing through a plane intersecting the mold chamber or matrix and toward which shrinkage of an ingot cast in the mold converges during solidification of the ingot.

In accordance with a further feature of the invention, as applied to corrugated or rippled bigend-down molds, the vertically extending corrugations or ripples terminate substantially above the bottom face of the mold, preferably from three to eight percent of the height of the matrix, the matrix walls being substantially smooth from the bottoms of the corrugations or ripples to the convex bottom edge. Preferably, the non-corrugated lower matrix side wall portions are tapered upwardly and'inwardly considerably more than the remainder of the side walls. Big-end-down molds with smooth or non-corrugated side walls also preferably should have the-lower five to eight percent of the side walls tapered inwardly and upwardly more than the remainder of the side walls. The greater bottom taper in a non-corrugated big-end-down mold increases the ease with which the bottom part of the mold can be separated vertically from the bottom part of the ingot. Consequently, damaging of the lower end of the mold by spelling, cracking, or otherwise is minimized.

An illustrative embodiment of the invention is shown in the accompanying drawings, in which:

Figure l is a central vertical sectional view of a stool and big-end-down mold embodying the invention;

Figure 2 is a top plan View of the mold shown in Figure 1; I

Figure 3 is a bottom plan view of the mold shown in Figures 1 and 2; and

Figure 4 is a fragmentary vertical sectional view of the stool and mold bottom portion drawn on an enlarged scale.

The mold assembly shown in Figures 1 and 4 includes a stool A and a mold proper B supported on the stool. The stool has lugs I for holding the mold against lateral shifting but otherwise is substantially flat or planar on its top face 2. The bottom face 3 of the mold proper is flat or planar and rests directly upon the stool top face 2 in sufficiently intimate surface contact with the face 2 to form a seal through which molten ingot metal poured into the mold will not escape.

As shown in Figures 1 and 4, the corrugations l of the matrix side walls 5 die or flatten out in a zone indicated generally by. the line X. From the level X to the bottom of the mold proper B, the matrix side walls 5 are tapered upwardly-inwardly decidedly more than the matrix walls above the level X. This more highly tapered portion is shown as extending throughout about three percent of the mold height, but as stated above it' may extend throughout as much as eight percent of the height. The lower portions (from three to eight percent) of the side walls preferably are more highly tapered in this way whether the matrix walls are corrugated or not.

By removing the lower portions of the corrugations, that is, stopping the corrugations at about the level X, the mold is made relatively smooth in the zone most subject to the cutting action of splattered ingot metal, and erosion and cracking of the lower matrix walls are reduced.

About five to eight percent of the bloom produced from a big-end-down ingot ordinarily is cropped and discarded, sothat corrugations in the extreme bottom part of the mold could have no beneficial effect upon the ingot. Consequently, elimination of the corrugations from the bottom portions of the matrix side walls achieves the desirable result of increasing the mold life without any sacrifice of quality of the ingots produced in the mold.

As previously stated, an important feature of the invention is the provision of a smoothly rounded convex edge between the lower portions of the matrix side walls and the bottom face of the mold. In the construction shown such a convex edge 6 intervenes and connects the lower matrix walls 5 and the bottom face 3 of the mold proper B. The radius of the convex edge 6 should be quite small. In the mold shown, which has a total height of about seventy-four inches and other dimensions approximately to scale, the radius of the edge 6 is approximately three quarters of an inch.

When hot molten ingot metal is poured into the mold assembly it strikes the stool or mold bottom A and splatters against the matrix walls 4. Because of the absence of the sharp corner edge between the side walls and mold bottom face the bottom part of the mold does not spall, crack or otherwise wear out as rapidly as prior big-enddown molds which have been characterized by the sharp corner edges referred-to. The effective life of the entire mold is thus lengthened. Inasmuch as the mold wears out more nearly evenly throughout its length, its progressively deteriorating condition is more apparent and it is less likely that an operator will continue to use a mold incapable of producing sound surfaced ingots.

Neutral lines of peripheral shrinkage are indicated at NN and N'-N'.

The ingot mold shown by way of example embodies the invention in a preferred form but it will be understood that changes may be made without departing from the invention as described and as set forth in the appended claims.

I claim:

1. In a mold assembly for casting metal, a bigend-down mold proper; and a stool on which the mold proper is supported, the matrix walls of the mold proper and the lower face of the mold proper merging in a smoothly rounded convex edge. I

2. In a mold assembly for casting metal, a bigend-down mold proper; and a stool on which the mold proper is supported, the lower portion of the matrix walls of the mold proper being highly tapered and merging with the lower face of the mold proper in a smoothly rounded convex edge.

3. A big-end-down-mold member open at its bottom and having a bottom face adapted to be supported on a stool in intimate surface contact with the top face of the stool, the matrix walls and the bottom face of said member merging in a smoothly rounded convex edge.

4. A big-end-down mold member open at its bottom and having a bottom face adapted to be supported on a stool in intimate surface contact with the top face of the stool, the matrix walls and the bottom face of said member merging in a smoothly rounded convex edge the radius of which is about 2 to 3 per cent of the maximum horizontal dimension of the mold matrix along a neutral axis.

5. In a mold assembly for casting metal, a bigend-down mold proper; and a stool on which the mold proper is supported, the lower portion of the matrix walls of the mold proper comprising from three to eight percent of the matrix height being highly tapered and merging with the lower face of the mold proper in a smoothly rounded convex edge.

EMIL GATHMANN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,649,522 Gathmann Nov. 15, 1927 1,738,882 Furness Dec. 10, 1929 1,973,374 Farabaugh Sept. 11, 1934 2,071,906 Stevens Feb. 23, 1937 OTHER REFERENCES Ingot and Ingot Molds, by Brearly, pages 88 and 89. 

